How To Install Transmission Cooler Lines To The Radiator

How To Install Transmission Cooler Lines To The Radiator

If you are reading this post, it simply means you want to learn about how to install transmission cooler lines to the radiator.

Let’s quickly dive into it.

The transmission cooler keeps your vehicle’s transmission at optimum temperatures. Although, it adds to the part that functions alongside the radiator to draw heat from the transmission fluid. As much as every vehicle has factory transmission cooler lines, it’s crucial to maintain yours for maximum efficiency and to last longer than expected.

Peradventure, if you suspect that your transmission cooler lines are showing symptoms of the issue, the best you can do is to get in touch with a transmission specialist. Perchance, repairing, replacing, or even installing the transmission cooler line of your vehicle’s transmission could take quite some time.

You might leave your car in the professional repair shop for hours or, at most, a day since reaching out for the cooling lines is complex. So, be sure to spend more on repair or installation.

Moreover, this informative post would tend to examine, explore and proffer solutions to these specific problems and questions, such as, what transmission line goes to the radiator, how to install transmission cooler lines to the radiator, should the transmission cooler be before or after the radiator, do you have to bleed transmission cooler lines, can you over cool transmission fluid, and more.

So far, studying through this work would be in your best interest!

How Do Transmission Cooler Lines Connect To The Radiator?

Transmission cooler lines do not connect to the radiator but, perchance, are fixed to the radiator through an in-line path, known as the return line, which carries cool fluid from the radiator to the transmission.

What Transmission Line Goes To The Radiator?

Transmission has two lines, the inlet line and the outlet line, in which trans liquid flows through the transmission to the radiator. However, the transmission line that goes to the radiator via the transmission is the outlet line which is the cooling line consisting of a brass barb and a flare fitting at both ends, respectively.

The function of this outlet line is to allow the passage of cooled fluid from the radiator for the proper maintenance and reduction of heat in the cooling system.

How To Install Transmission Cooler Lines To The Radiator?

Transmission Cooler Lines To The Radiator .

To install the transmission cooler lines to your vehicle’s radiator, you need some tools before mounting the cooler and connecting the lines as necessary.

Materials/Tools Needed.

  • Dyke pilers
  • Razor knife
  • Standard screwdriver or 5/16-inch nut driver
  • 5/8 inch-Open End Wrench
  • Hacksaw or small pipe cutter
  • Other installation kits.

Here you have each installation procedure categorically;

Mounting The Transmission Cooler

  • Identify the 4 mounting rods, 4 1×1 foam pads, and 4 mounting clips.
  •  Install each of the 4 mounting rods to the trans cooler.
  •  Peel off the paper lining of the 1×1 foam and slide each to the mounting rod as you strike them against the trans cooler.
  •  Attach the looped hose to the cooler assembly and hold it in the desired setting.

Note: Don’t use excessive pressure/force when you push the mounting rod through the radiator to avoid damage.

  • Use the mounting clips in the correct direction as you install each on the mounting rod. Perchance, clinch each until you slightly compress the 1×1 foam pads.
  • Cut off any excess from the mounting rods

Locating The Transmission Lines.

After mounting the rods, locate the lines with the steps below.

  • Find the 2 transmission oil lines that run from the trans to the radiator, usually steel lines at the lower/bottom of the radiator tank.
  • As the cooler is in series connection with the factory radiator cooler, determine the return line to the trans as you warm up your vehicle. However, feel the trans lines, and by implication, the colder line of the two is the return line.

When you have located the trans lines, the hose connection is next.

Hose (Line) Connections.

Check out the steps below!

  • Disconnect from the radiator the return trans cooler line.
  • Use the Insta-dapt Adapter fitting and install it onto the radiator with a female or male end.

Note: The Insta-dapt fitting is of a ½ inch to 20 inches thread and fits most cars with 5/16 inches trans cooler lines, but if your vehicle is not compatible, visit www.derale for available options.

With the supplied hose clamp, attach and tighten it gently.

Warning: Keep hoses away from sharp edges, moving parts, and hot engine components as you route them. Similarly, you should carefully bend them at most 3 inches.

System Check

  • You start your vehicle and check all connections in case of a leak.
  • Put the vehicle in a neutral position and check the trans fluid level.
  • You could add trans fluid if necessary.
  • Drive your vehicle to ensure the transmission is warm as you recheck the fluid level.

Note: All accessories you would tend to install must be done by a professional to avoid

harming the trans cooler systems since you are unfamiliar with vehicle components.

Should I Bypass The Radiator When Installing The Transmission Cooler?

No, it would be best if you didn’t bypass the radiator when installing the transmission. Though it doesn’t worth it at all.

The effect of bypassing the radiator is that there would emanate a series of damage to the cooling system leading to much wear and tear of the mechanical components of the transmission, failure of the transmission, and high fuel consumption.

Similarly, your radiator would be prone to severe damage due to increased heat compared to the standard level of heat flow rate. On the other hand, the increase in the heat level of the radiator would also constitute the coolant’s temperature to rise since the engine can’t recover the heat from the combustive chamber to the outside air.

Should The Transmission Cooler Be Before Or After The Radiator

The installation of the transmission cooler before or after depends on your choice; if not, it would be your manufacturer’s instruction. Perchance you want to install your transmission cooler before the radiator, no issue.

It will also enhance additional airflow to cool and provide you with access to work on the cooler lines in the future. By the research and experience gathered, I recommend you install the transmission cooler after the radiator to facilitate the return of the fluid to the transmission.

The essence of this is to avoid overheating of the transmission fluid. In any case, make sure to install the cooler in the best location of your car, as regards a position with maximum airflow.

Do You Have To Bleed Transmission Cooler Lines?

No, you don’t have to bleed out air from your transmission cooler lines. However, it is a somewhat open system to start with; Since the transmission would purge out any air in it by itself through the help of the vent valve on the top of the transmission, perchance, the transmission should only build enough pressure through its pump, clutch pistons, and cooler lines.

But on the conserve, if you insist on bleeding your transmission cooler lines, the instruction below should be helpful.

Here you have the best tips as you use the hand vacuum pump at the slave cylinder;

  • Fill the reservoir with fluid as you get under the truck of your vehicle.
  • Check for the bleeder valve, such as the brake caliper at the slave cylinder.
  • With a rubber hose that could fit in tightly, attach the vacuum pump to the valve.
  • Pull the vacuum with the pump as you loosen the hose.
  •  Use the catch can with most vacuum pumps to catch the fluid.
  • The system should bleed when all the air bubbles are gone. Perchance might take a while, so keep checking the fluid in the reservoir, as you don’t let it run out.
  •  After the air is out, you should be able to press the clutch pedal multiple times to make sure you have a correct repair.

If you don’t have access to the vacuum pump, try using the gravity bleed system.

Tips: This only works well at some times!

Here you have the steps;

  • Open the bleeder screw enough to allow fluid to drip out.
  • Take the cap off the reservoir as you allow the system to drain.
  • Check the fluid level so as not to run out of fluid, or it could take about one full bottle.
  • You should drain ½ of the fluid, tighten the bleeder valve, and install the reservoir cap.
  • The system should bleed out as you pump the clutch pedal multiple times.

I hope this is helpful!

Can You Over Cool Transmission Fluid?

For sure, it is unnecessary to over-cool the transmission fluid!

Although, some transmission issues emanate from extreme cold weather. Essentially, metal parts contract while exposed to colder weather which would result in these parts’ mates loosening up, wearing faster due to friction from a reduction in clearances between components, and, perchance, developing leaks from hardening and shrinkage gaskets and seals.

It is vital to recall that the optimal temperature of your transmission is about 180 degrees Fahrenheit, so the viscosity of the fluid changes and could get more viscous at a lower temperature.

As such happens, the transmission (AT) fluid would fall to 32 degrees Fahrenheit or even below. Thus, the fluid becomes significantly higher in viscosity level, restricting its flow to lubricate the transmission components as it would emanate a very fast wearing and tearing. However, the use of synthetic Automatic Transmission fluid is highly recommended rather than petroleum-based ATFs.

Now that you have the real gist, don’t over-cool your transmission!

Does It Matter Which Way A Transmission Cooler Is Mounted?

Of course, yes, it does! Although you could mount a transmission cooler in vertical or horizontal positions of your choice in your vehicle, be sure that the location or place at which the cooler has maximum airflow; enhances the cooling tendency of the transmission cooler or its effectiveness.

Are Transmission Coolers Directional?

Of course, yes, transmission coolers are directional. In essence, the flow of the transmission cooler is specific, which is why the vehicle’s cooler would always have engravings indicating the flow direction between the radiator and the transmission in the form of outlet lines and inlet lines in the cooler. Thus, the transmission coolers are essentially directional.

What Does A Transmission Cooler Bypass Valve Do?

The bypass valve is functional in your vehicle’s transmission cooling and heating systems. The bypass valve regulates the flow and direction of oil to enhance self-control and operate the temperature of the transmission system. Similarly, the bypass valve in OEMs often uses the TVB to hold oil in the transmission during cold weather as it heats the oil promptly to reduce frictional force internally.

The bypass valve operation minimizes fuel consumption in cold conditions; in hot conditions, the valve allows for flowing to your vehicle’s auxiliary oil cooler to maximize cooling performance.


To summarize this post, it is essential to have a pre-knowledge of the transmission cooling system of your vehicle as a driver to help you factor out the functions of the cooler lines.

As much as your vehicle’s engine operates and accelerates, its temperature increases. You should regularly check the transmission system; if there is severe damage, you must install a new one.

However, during the first week after installing a transmission cooler and its oil/fluid, occasionally check your connections for any leak and the hose clamps to ensure they are intact. A professional mechanic is vital for the above installation procedures.

Now you can drive your vehicle with high self-assurance and peace of mind knowing that your installed transmission cooler is perfect. Do like and share this informative post with others!

Scroll to Top